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OUTLOOK

A flooding event may be generally divided into the following three temporal stages, during which different users require different types of information.

Before the flood: The main components in this stage are the rainfall and flood forecasts, signaling when and where problems may occur.

During the flood: Frequent real-time observations are required to follow how the event develops and maximize situation awareness.

After the flood: Properly quality controlled, stored and documented observations, forecasts and other relevant information are needed to facilitate post-event analyses.

However, this division is not straight-forward. For example, real-time observations (during the flood) can be important before the flood and forecasts (before the flood) can be important during the flood.

Further, flood-related information (observations, forecasts) is available from systems operating over different spatial domains.

The city: A city may operate its own flood forecasting system or be included in a small regional system.

The region/country: Several regions and countries operate forecasting systems.

The continent (Europe): A range of hydrological modelling systems have been set up for flood forecasting at the Pan-European level.

Figure 1 illustrates these two dimensions, i.e. the temporal phase and the spatial domain.

Generally, local systems and information provide the highest value for the end-users in all flood phases (Figure 2). These systems may be based on highly detailed data on catchment characteristics (surface and sub-surface) and use hydraulic equations to describe local water fluxes (Table 1). However, local systems are lacking in many cities which are thus dependent on purely hydrological information from national or even continental level. Today, this information is often too coarse in both time and space for being of real use in an urban context but this may change as the resolution, quality and availability of both meteorological and geographical data are rapidly increasing.

Table 1. Examples of data and models used in cities with local systems (left) and cities covered by larger-scale forecasting systems (right).

Local

Regional/National/Continental

Network of high-resolution rainfall gauges

X-band high-resolution radar

High-resolution DEM and land-use info.

Hydraulic model incl. sewers and inundation

+ High level of detail and accuracy

One lower-resolution gauge?

C-band lower-resolution radar

Lower-resolution DEM and land-use info.

Hydrological model for runoff and discharge

+ Available and computationally inexpensive

In MUFFIN, we aim at increasing the end-user value of information related to urban floods by research and development at all scales as well as adaptation and promotion of existing material (Figure 2).

Figure 2. End-user value and MUFFIN activities.

The research and development will be performed in three cities: Aalborg (DK), Rotterdam (NL) and Helsinki (FI). During the first phase of the project, local forecasting systems will be developed and optimized for selected sub-basins in these cities. In parallel, the hydrological model HYPE (http://hypeweb.smhi.se/) will be developed for high-resolution modelling and set up for the same sub-basins. In the second phase of the project, coordinated forecasting experiments will be carried out in order to explore the benefits and limitations of each type of model system as well as the prospect of combining them. See further DEVELOPMENT.